Artificial turf having fibers with different melting points

ABSTRACT

An artificial turf system is for installation over a receiving surface. The artificial turf system comprises a flexible sheet member to be laid over the receiving surface via its lower surface. It comprises first yarns having a first melting point; second yarns, distinct from the first yarns and having a second melting point; and third yarns, having a third melting point, with all yarns extending upwardly from the upper surface of the sheet member. The third melting point is lower than the first and second melting point. The artificial turf system undergoes a heat treatment at a temperature higher that the third melting point prior to installation through which third yarns at least partially fuse with part of one of the first yarns and the second yarns. Further described is a method of manufacturing the artificial turf system.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. provisional patent application 62/776,709 filed Dec. 7, 2018, the specification of which is hereby incorporated herein by reference in its entirety.

BACKGROUND (a) Field

The subject matter disclosed generally relates to playing fields and more particularly to artificial sports and amusement playing fields. The subject matter disclosed may also relate to artificial turf surface of all kinds (i.e., artificial sports playing fields, artificial amusement playing fields, gymnasium surfaces, backyard surfaces and the like).

(b) Related Prior Art

The use of artificial or synthetic turf has been growing steadily in recent years. Artificial turf is a surface of synthetic fibers made to look like natural grass. It is most often used in arenas and fields for sports that were originally or are normally played on grass.

However, it is now being used in other applications such as, for residential lawns or landscapes, for pet areas, for child playgrounds, for golf courses and putting greens, on roofs, decks and patios as well.

The advantages of synthetic turf are numerous. For example, synthetic turf does not need to be cared as much as real grass. Moreover, synthetic turf is more durable.

There exist on the market numerous artificial or synthetic turf systems aiming to provide improved comfort, sufficient traction, and shock absorbent characteristics. For example, and now referring to PRIOR ART FIGS. 1A and 1B, there is shown a regular artificial turf system 10 which includes a sheet member 12 made of a flexible material and a plurality (substantially straight) fibers 14 upwardly extending from the sheet member 12. The plurality of fibers 14, which creates a carpet-like top layer, therefore includes a series of regularly spaced apart (or equally spaced) parallel rows of backstitches 16. For providing the shock absorbent characteristic, straight fiber support and sufficient traction for the desired sport to the artificial turf system 10, a plurality of rubber granules and/or sand (not shown, such as from recycled tires) are often disposed on the artificial turf system 10.

Even though the rubber granules and/or sand used in modern artificial synthetic turf tend to contain lower quantities of harmful substances, such as metal (e.g., lead and zinc), inorganic and organic compounds, it may significantly increase health problems for those playing/walking on it, it may significantly increase the surface temperature above the surface covering panel and it may lead to some other environmental problems. The infill also becomes compacted with time affecting directly shock absorption and traction of the artificial synthetic turf to the detriment of the players.

According to another example and referring now to PRIOR ART FIGS. 2A and 2B, there is shown an artificial turf system without infill for installation over a receiving surface (not shown). The artificial turf system 100 includes a sheet member 102 made of a flexible material. The sheet member 102 defines a first surface or primary backing for interfacing with the receiving surface and a second surface. The artificial turf system 100 further includes a plurality of primary yarns 108 made of straight fibers (monofilament, parallel fibrillated or fibrillated fibers) which are upwardly extending from the second surface of the sheet member 102 and a plurality of secondary yarns 110 made of textured fibers or thatch fibers which are upwardly extending from the second surface of the sheet member 102. The plurality of secondary yarns 110 are positioned on the sheet member 102 such as to intersperse with the plurality of primary yarns 108.

The plurality of secondary yarns 110 made of textured or thatch fibers represent less than 50% in weight (aka face weight) of the plurality of primary and secondary yarns 108, 110 taken together. Therefore, the straight fiber support, traction and shock absorbent characteristics are not optimized.

The plurality of primary and secondary yarns 108, 110 which creates together a carpet-like top layer 112 includes a series of regularly spaced apart (or equally spaced) parallel rows of backstitches 114, 116 tufted or knitted in straight line, in “zigzag” or in a S pattern. The series of regularly spaced apart parallel rows of backstitches 114, 116 include a series of regularly spaced apart parallel rows of backstitches 114 made of the plurality of primary yarns 108 and a series of regularly spaced apart parallel rows of backstitches 116 made of the plurality of secondary yarns 110, which are interspersed within the series of regularly spaced apart parallel rows of backstitches 114 made of the plurality of primary yarns 108.

The fact that the artificial turf system 100 combines both the plurality of primary yarns 108 made of straight fibers and the plurality of secondary yarns 110 made of textured or thatch fibers provides straight fiber support and player traction to the artificial turf system 100. However, according to this configuration, the straight fiber support, players traction and shock absorbent characteristic are not optimized.

There is therefore a need for improved artificial turf system without infill that optimizes straight fiber support, player traction and shock absorbent characteristics and that would overcome the above-noted drawbacks.

SUMMARY

According to an embodiment, there is provided an artificial turf for installation over a receiving surface, the artificial turf comprising: a sheet member made of a flexible material, the sheet member comprising a lower surface to be laid over the receiving surface and an upper surface; first yarns having a first melting point, the first yarns extending upwardly from the upper surface of the sheet member; second yarns distinct from the first yarns and having a second melting point, the second yarns extending upwardly from the upper surface; and third yarns distinct from the first yarns and the second yarns and having a third melting point, the third yarns extending upwardly from the upper surface, wherein the third melting point is lower than the first melting point and the second melting point, and wherein, after the artificial turf has undergone a heat treatment at a temperature higher that the third melting point, the third yarns are at least partially fused with at least part of one of the first yarns and of the second yarns.

According to an aspect, one of the first yarns and the second yarns are made of straight fibers.

According to an aspect, after having undergone the heat treatment, the yarns made of straight fibers extend upwardly beyond the other yarns.

According to an aspect, one of the first yarns and the second yarns are made of one of textured fibers and thatch fibers and are not straight fibers.

According to an aspect, one of the first yarns and the second yarns are made of polyamide.

According to an aspect, the third yarns are made of olefin material, comprising one of polyethylene, polypropylene, polyester (PET), and a combination of polyethylene and polypropylene.

According to an aspect, at least one of the first yarns, the second yarns and the third yarns are backstitched to the sheet member.

According to an aspect, the first yarns, the second yarns and the third yarns are backstitched to the sheet member according to parallel backstitches.

According to an aspect, the backstitches are equidistant.

According to an aspect, the second yarns and the third yarns are combined into combined yarns and backstitched together to the sheet member.

According to an aspect, the first yarns comprise one of flat face fibers, monofilament fibers, monotape yarns, fibrillated yarns, polyfilament fibers, parallel fibrillated or fibrillated fibers, and split fibers.

According to an aspect, the first yarns have a cross section that has a shape of one of a rectangular cross-section ribbon, a diamond, a horseshoe, a U shape, a V shape, an S shape and a flat rectangular general cross section with its shorter sides rounded.

According to an aspect, the first yarns are straight, the second yarns are textured or thatch, and wherein the first yarns extend beyond the seconds yarns relative to the upper surface of the sheet member.

According to an aspect, the second yarns are more rigid than the first yarns.

According to an aspect, the second yarns are made of a plurality of filiform formations arranged in tufts.

According to an aspect, the first yarns have a first length, the second yarns have a second length at least equal to the first length, the first yarns extend to a first elevation from the upper surface, and the second yarns extend to a second elevation from the upper surface lower than the first elevation.

According to an aspect, at least one of the first yarns, the second yarns and the third yarns is backstitched as tufts with the tufts having a tufting gauge between three sixteenth of an inch ( 3/16″) and three quarter of an inch (¾″).

According to an embodiment, there is provided a method of manufacturing an artificial turf, comprising: stitching to a sheet member (1) first yarns having a first melting point, (2) second yarns distinct from the first yarns and having a second melting point, and (3) third yarns distinct from the first yarns and the second yarns and having a third melting point lower than the first melting point and the second melting point, wherein the first yarns, the second yarns and the third yarns extend upwardly from the sheet member; submitting the artificial turf to a heat treatment at a temperature equal to or above the third melting point but under the first melting point and the second melting point, whereby the third yarns at least partially fuses with at least one of the first yarns and the second yarns.

According to an aspect, the method further comprises maintaining the heat treatment between 2 seconds and 10 seconds.

According to an aspect, the method further comprises performing the heat treatment with a heat source of a temperature of between 125 and 225 degrees Celsius.

According to an aspect, submitting the artificial turf to a heat treatment comprises having the yarns face a heat source.

Features and advantages of the subject matter hereof will become more apparent in light of the following detailed description of selected embodiments, as illustrated in the accompanying figures. As will be realized, the subject matter disclosed and claimed is capable of modifications in various respects, all without departing from the scope of the claims. Accordingly, the drawings and the description are to be regarded as illustrative in nature and not as restrictive and the full scope of the subject matter is set forth in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

FIG. 1A is a perspective partial view showing the top surface of an infilled artificial turf system in accordance with the PRIOR ART;

FIG. 1B is a perspective partial view showing the bottom surface of the infilled artificial turf system in accordance with the PRIOR ART;

FIG. 2A is a perspective partial view showing the top surface of a non-infilled artificial turf system in accordance with the PRIOR ART;

FIG. 2B is an elevation view showing the non-infilled artificial turf system of FIG. 2A in accordance with the PRIOR ART;

FIG. 3 is a perspective view showing the top surface of an artificial turf system in accordance with an embodiment;

FIG. 4 is a perspective partial close up view showing the artificial turf system of FIG. 3;

FIG. 5 is a perspective partial close-up view of the artificial turf system of FIG. 3;

FIG. 6 is a perspective partial view showing the bottom surface of the artificial turf system of FIG. 3;

FIG. 7 is a schematic showing a cross-section side view of the artificial turf system before heat treatment according to an embodiment;

FIG. 8 is a schematic showing a cross-section side view of the artificial turf system of FIG. 7 after heat treatment;

FIG. 9 is a schematic showing a cross-section side view of the artificial turf system before heat treatment according to another embodiment; and

FIG. 10 is a schematic showing a cross-section side view of the artificial turf system of FIG. 9 after heat treatment.

DETAILED DESCRIPTION

The realizations will now be described more fully hereinafter with reference to the accompanying figures, in which realizations are illustrated. The foregoing may, however, be embodied in many different forms and should not be construed as limited to the illustrated realizations set forth herein.

With respect to the present description, references to items in the singular should be understood to include items in the plural, and vice versa, unless explicitly stated otherwise or clear from the text. Grammatical conjunctions are intended to express any and all disjunctive and conjunctive combinations of conjoined clauses, sentences, words, and the like, unless otherwise stated or clear from the context. Thus, the term “or” should generally be understood to mean “and/or” and so forth.

Recitation of ranges of values and of values herein or on the drawings are not intended to be limiting, referring instead individually to any and all values falling within the range, unless otherwise indicated herein, and each separate value within such a range is incorporated into the specification as if it were individually recited herein. The words “about,” “approximately,” or the like, when accompanying a numerical value, are to be construed as indicating a deviation as would be appreciated by one of ordinary skill in the art to operate satisfactorily for an intended purpose. Ranges of values and/or numeric values are provided herein as examples only, and do not constitute a limitation on the scope of the described realizations. The use of any and all examples, or exemplary language (“e.g.,” “such as,” or the like) provided herein, is intended merely to better illuminate the exemplary realizations and does not pose a limitation on the scope of the realizations. No language in the specification should be construed as indicating any unclaimed element as essential to the practice of the realizations.

In the following description, it is understood that terms such as “first”, “second”, “top”, “bottom”, “above”, “below”, and the like, are words of convenience and are not to be construed as limiting terms. The terms “top”, “upper”, “bottom”, “lower”, “vertical”, “horizontal” and the like are intended to be construed in their normal meaning in relation with an artificial turf surface comprising the present product, thus in relation with normal installation of the product.

In embodiments, there are disclosed artificial turf systems for applying on receiving surfaces.

Referring now to the drawings, and more particularly to FIGS. 3 to 6, there is shown an artificial turf system 200 without infill for installation over a receiving surface (not shown) in accordance with an embodiment. The artificial turf system 200 includes a sheet member 202 made of a flexible material. The sheet member 202 defines a first (lower) surface 204, or primary backing for interfacing with the receiving surface, and a second (upper) surface 206. Hereinafter, the expressions lower surface 204 and upper surface 206 will be used in a non-limiting manner since referring to most common installation.

The sheet member 202, that may comprise several sheet members used together, may include materials made of, but not exclusively limited to, Olefin (Polypropylene), Polyamide (Nylon), Polyethylene Terephalate (PET) virgin or a recyclable material, Polyester Woven and non-woven, cordura material, either with a ratio of 100% of these materials or a combination of these materials. The sheet member 202 may be manufactured in a closed-weave woven, an opened-weave woven, leno weave cross weave or non-woven material suitable to maximize ability to tuft, to provide tuft bound to stitched yarns, to provide dimensional stability, to provide the desired hardness-flexibility ratio to the sheet member, to provide penetration of the sheet member 202 by a secondary coating applied to the bottom of the sheet member 202 and which can be made of polyurethane or latex or acrylic or some other material suitable to use as a binder to hold the fibers in place to the sheet member 202 or to allow the binding of the fibers to the sheet member 202 by heat, pressure or with Polyurethane.

The thickness of the sheet member 202 is typically substantially uniform and ranges typically between about two tenth (0.20) of a mm and two (2) mm.

The artificial turf system 200 further comprises first yarns 212 made of straight fibers (substantially straight fibers) which are upwardly extending from the upper surface 206 of the sheet member 202. The artificial turf system 200 further comprises second yarns 214 made of textured fibers or thatch fibers which are upwardly extending from the upper surface 206 of the sheet member 202. Because of their particular curl-shape, the second yarns 214 position themselves on the sheet member 202 in random (or all) directions, resulting in the second yarns 214 substantially surrounding the first yarns 212. The artificial turf system 200 further comprises third yarns 216, wherein the third yarns 216 are at least partially fused with at least one of the first yarns 212 and the second yarns 214.

The first yarns 212, second yarns 214 and third yarns 216 create together a carpet-like top layer 210 which comprises series of regularly spaced apart (or equally spaced) parallel rows of backstitches 222. According to realizations, the rows are either straight, in S or Z patterns or any other regular shape having a longitudinal orientation, a width and a period, or a combination of a plurality of the patterns thereof. The rows are further tufted or knitted.

According to realizations, backstitches 222 are separated by a substantially constant backstitch distance, thus equidistant, ranging typically between about one sixteenth of an inch ( 1/16″) and one half of an inch (½″).

According to a realization, rows of backstitches 222 of the first yarns 212 are stitched parallel to each other with intermediate rows of backstitches 222 of second yarns 214 and third yarns 216, or backstitches 222 of a combination thereof. Thus, according to realizations, rows of backstitches 222 of first yarns 212 may be separated by one or more rows of backstitches 222 of any of second yarns 214, third yarns 216 and a combination of second yarns 214 and third yarns 216, aka combined yarns. According to a typical realization (see FIGS. 7 to 10), a single row of backstitches 222 of a combination of second yarns 214 and third yarns 216 is stitched between two parallel rows of backstitches 222 of first yarns 212.

According to an embodiment, at least part of the backstitches 222 are made with a combination of the first yarns 212 and at least one of the second yarns 214 and the third yarns 216. Thus, a yarn combination elevated from the same backstitch 222 may comprise a substantially straight yarn and a low-elevation yarn as final yarns as will be discussed in more details below.

Regardless of the realizations discussed before, the first yarns 212 are interspersed within at least one, and typically with both the second yarns 214 and the third yarns 216.

The fact that the artificial turf system 200 combines first yarns 212 made of substantially straight fibers and a mix of low-elevation typically textured or thatch fibers composed of a combination of second yarns 214 and third yarns 216 provides improved straight-fiber support to the first yarn 212, as well as improved player traction and shock absorbent characteristics to the artificial turf system 200.

The material of the first yarns 212 is characterized in having a first melting point that is higher relative to the melting point of at least the third yarns 216. The material of the first yarns 212 typically comprises polyamide material and the like.

The shape and construction of the first yarns 212 may include flat face fibers, monofilament fibers, monotape yarns, fibrillated yarns, polyfilament fibers, parallel fibrillated or fibrillated fibers and split fibers. The first yarns 212 may be made from extrusion and take different shapes such as a rectangular cross-section ribbon, diamond, horseshoe, U, V, S shape or a flat rectangular general cross section with its shorter sides rounded. Its cross-section may feature one or more curved-convex projections for instance. When backstitched to the sheet member 202, the straight (or substantially straight) first yarns 212 are set upwardly extending from the upper surface 206 to simulate blades of grass of natural grass cover.

According to a realization, the first yarns 212, the second yarns 214 and the third yarns 216 have respectively a first original cross section area, a second original cross section area and a third original cross section area perpendicular to their length before undergoing the heat treatment, and wherein the cross section areas take different shapes such as a rectangular cross-section ribbon, diamond, horseshoe, U, V, S, W shape or a flat rectangular general cross.

The material of the second yarns 214 is characterized in having a second melting point that is higher relative to the melting point of at least the third yarns 216. The material of the second yarns 214 typically comprises polyamide material and the like.

The shape and construction of second yarns 214 may include straight or texturized monofilament, monotape yarn and fibrillated yarn.

The material of the third yarns 216 is characterized in having a third melting point that is lower relative to the melting point of the first yarns 212 and the second yarns 214. The material of the third yarns 216 typically comprises olefin material, such as polyethylene, polypropylene, polyester (PET), a combination of polyethylene and polypropylene and the like. It can also be Polyamide core yarn wrapped with Olefin material

The shape and construction of the third yarns 216 may include straight or texturized monofilament, monotape yarn and fibrillated yarn. Further, the third yarns 216, as shown on FIGS. 7 to 10, may be straight, substantially straight, relatively textured or strongly textured at the time of stitching.

It should be noted that even though the first yarns 212, second yarns 214 and third yarns 216 are characterized by their melting points, one should construe a high melting point and a low melting point as relative characteristics. Further, the first yarns 212 and the second yarns 214 having a high melting point does not necessarily mean that they have the same melting point.

Back to the yarn materials, the selection of the materials of the first yarns 212, second yarns 214 and third yarns 216 makes it possible to put the upper surface 206 of the sheet member 202 under a heat source and have the third yarns 216 partially melting under heat treatment to at least partially fuse with at least one of the first yarns 212 and second yarns 214.

Referring now additionally to FIGS. 7 to 10. Typically, the third yarns 216 when melting tend to shrink and partially vertically collapse close to the upper surface 206, decreasing in elevation.

According to a realization, the third yarns 216 when melting at least partially fuse with the second yarns 214 at a substantially low elevation relatively to the total elevation of the artificial turf system 200. Accordingly, the fused second yarns 214 and third yarns 216 combine in providing support to the substantially straight first yarns 212.

Typically, the heat source is used to perform heat treatment to the stitched first yarns 212, second yarns 214 and third yarns 216 at a temperature of about between one hundred and fifty (150) to two hundred (200) degrees Celsius. The heat treatment is typically maintained over a heated surface for about between two (2) and ten (10) seconds for the third yarns 216 to partially melt and at least partially fuse with one of the first yarns 212 and second yarns 214 while maintaining at least partially a yarn structure.

According to a realization, the physical characteristics of the second yarns 214 are selected to obtain second yarns 214 that are more rigid than the first yarns 212, therefore having the second yarns 214, when a low ratio of third yarns 216 are fused with the second yarns 214, providing alone a good degree of support to the straight fibers while having the first yarns 212 providing the desired texture. These desired physical characteristics may be commonly obtained through selection of a more rigid material for the second yarns 214 than for the first yarns 212. Alternatively, a process (physical or chemical) over the second yarns 214 modifying its physical characteristics is used to obtain the desired rigidity.

The plurality of second yarns 214, while described herein as textured fibers or thatch fibers, may not require, according to one realization, to be textured. The second yarns 214 may not be textured, textured before stitching or textured after its stitching. However, it is referred to in all realization herein provided as “textured” to distinguish the second yarns 214 from the first “straight” yarn 212. Regardless of its texture, the second yarns 214 provide support to the substantially straight first yarns 212.

According to realizations, the second yarns 214 may be made of a plurality of filiform formations arranged in tufts so as to provide a better simulation of the blades of grass of natural grass cover. The manufacturing of second yarns 214 to provide the desired shape and structure may be performed, for instance, by means of a heat, chemical or mechanical treatment before use through which the second yarns 214 are crimped/curled.

Referring now particularly to FIG. 4 and according to realizations, the second yarns 214 consists of yarns, when pulled in a straight shape, of at least the same length as the first yarns 212. The second yarns 214, upon releasing tension therefrom to take its default shape and configuration, result in second yarns 214 that look shorter since they have a lower elevation relative to the upper surface 206.

Accordingly, the elevation 232 of the first yarns 212 from the upper surface 206 is illustrated as being greater than the elevation 234 (220) of the second yarns 214 from the same upper surface 206 regardless of the real length of the first and second yarns 212 and 214. The elevation 232 of the first yarns 212 from the upper surface 206 is also illustrated as greater than the elevation 236 of the third yarns 216 from the same upper surface 206 regardless of the real length of the first and third yarns 212 and 216, and particularly the length of the third yarn 216 before heat treatment. Thereby the second and third yarns 214, 216 in the final artificial turf system 200 are low-elevation fibers providing the desired fiber support to the first yarns 212, as to provide the desired player traction and shock absorbing characteristics.

According to a realization, the first yarns 212, the second yarns 214 and the third yarns 216 have respectively of a first original length, a second original length and a third original length before undergoing the heat treatment, and wherein the third length may vary from 12 mm to 70 mm before the heat treatment.

The tufting process of the first yarns 212, the second yarns 214 and the third yarns 216 can be performed by stitching both a combination of at least two of the first yarns 212, the second yarns 214 and the third yarns 216 concurrently, using the same needle. Alternatively, the first yarns 212, the second yarns 214 and the third yarns 216 may be stitched separately or independently, using distinct needles. The latter result in parallel backstitches 222 (see FIG. 6) of all of first yarns 212, of second yarns 214 and of third yarns 216.

Depending the selected tufting configuration, the tufting gauge typically vary from about three sixteenth of an inch ( 3/16″) to three quarter of an inch (¾″).

Regarding the mass of the first yarns 212, the total mass (total of the mass of each filament) of each filament of first yarns 212 may be in a range between 750 to 3,000 deniers per filament (DPF). The total mass of each first yarn 212 may be in a range between 750 to 3,000 deniers per filament (DPF) depending on the denier per filament (DPF) and number of filaments in the yarn. Preferably, the total mass of each filament of first yarn 212 is ranged between 750 to 2,000 deniers per filament (DPF).

Regarding the mass of the second yarns 214, the total mass (total of the mass of each filament) of each filament of second yarns 214 may be in a range between 750 to 3,000 deniers per filament (DPF). The total mass of each second yarn 214 may be in a range between 750 to 3,000 deniers per filament (DPF). depending on the denier per filament (DPF) and number of filaments in the yarn. Preferably, the total mass of each filament of second yarn 214 is ranged between 750 to 2,000 deniers per filament (DPF).

Regarding the mass of the third yarns 216, the total mass (total of the mass of each filament) of each filament of third yarns 216 may be in a range between 750 to 3,000 deniers per filament (DPF. The total mass of each third yarn 216 may be in a range between 750 to 3,000 deniers per filament (DPF depending on the denier per filament (DPF) and number of filaments in the yarn. Preferably, the total mass of each filament of third yarn 216 is ranged between 750 to 2,000 deniers per filament (DPF).

According to a realization, the artificial turf system 200 is manufactured according to a method comprising the following steps.

A first step comprises stitching to a sheet member having an upper surface and being made of a flexible material (1) first yarns 212 made of straight fibers having a first melting point, (2) second yarns 214 having a second melting point, and (3) third yarns 216 having a third melting point, wherein the first yarns 212, the second yarns 214 and the third yarns 216 are extending from the upper surface and the first yarns 212 extend substantially straight.

A second step comprises having the artificial turf system 200 to undergo a heat treatment heating the artificial turf system 200 above the third melting point but under the first melting point and the second melting point, thereby resulting in the third yarns 216 at least partially fusing with the first yarns 212 or the second yarns 214 and thereby participating in providing support to the first yarns 212.

According to embodiments, the method for heating the artificial turf system 200 comprises having the artificial turf system 200 facing a radiant heat source, or alternatively having the upper portion of the artificial turf system 200 at least partially immersed in a heated liquid such as liquid silicon in order for the tip of at least the third yarns 216 to be heated by the hot liquid and therefore to melt at least partially.

The artificial turf system 200 as described above may provide, over infill artificial turf systems, increase protection for children in playgrounds, may provide improved players traction and shock absorbent characteristics for sport fields of all kinds, and may have a reduced surface temperature. The plurality and nature of the second yarns 214 and third yarns 216 in sufficient quantity render the presence of rubber granules or other infill unnecessary to provide straight fiber support, while providing adequate traction for players and shock absorbent characteristics.

While preferred embodiments have been described above and illustrated in the accompanying drawings, it will be evident to those skilled/in the art that modifications may be made without departing from this disclosure. Such modifications are considered as possible variants comprised in the scope of the disclosure. 

1. An artificial turf for installation over a receiving surface, the artificial turf comprising: a sheet member made of a flexible material, the sheet member comprising a lower surface to be laid over the receiving surface and an upper surface; first yarns having a first melting point, the first yarns extending upwardly from the upper surface of the sheet member; second yarns distinct from the first yarns and having a second melting point, the second yarns extending upwardly from the upper surface; and third yarns distinct from the first yarns and the second yarns and having a third melting point, the third yarns extending upwardly from the upper surface, wherein the third melting point is lower than the first melting point and the second melting point, and wherein, after the artificial turf has undergone a heat treatment at a temperature higher that the third melting point, the third yarns are at least partially fused with at least part of one of the first yarns and of the second yarns.
 2. The artificial turf of claim 1, wherein one of the first yarns and the second yarns are made of straight fibers.
 3. The artificial turf system of claim 2, wherein, after having undergone the heat treatment, the yarns made of straight fibers extend upwardly beyond the other yarns.
 4. The artificial turf of claim 1, wherein one of the first yarns and the second yarns are made of one of textured fibers and thatch fibers and are not straight fibers.
 5. The artificial turf of claim 1, wherein one of the first yarns and the second yarns are made of polyamide.
 6. The artificial turf of claim 1, wherein the third yarns are made of olefin material, comprising one of polyethylene, polypropylene, polyester (PET), and a combination of polyethylene and polypropylene.
 7. The artificial turf of claim 1, wherein the first yarns, the second yarns and the third yarns are backstitched to the sheet member according to parallel backstitches.
 8. The artificial turf of claim 7, wherein the backstitches are equidistant.
 9. The artificial turf of claim 1, wherein the second yarns and the third yarns are combined into combined yarns and backstitched together to the sheet member.
 10. The artificial turf of claim 1, wherein the first yarns comprise one of flat face fibers, monofilament fibers, monotape yarns, fibrillated yarns, polyfilament fibers, parallel fibrillated or fibrillated fibers, and split fibers.
 11. The artificial turf of claim 1, wherein the first yarns have a cross section that has a shape of one of a rectangular cross-section ribbon, a diamond, a horseshoe, a U shape, a V shape, an S shape and a flat rectangular general cross section with its shorter sides rounded.
 12. The artificial turf of claim 1, wherein the first yarns are straight, the second yarns are textured or thatch, and wherein the first yarns extend beyond the seconds yarns relative to the upper surface of the sheet member.
 13. The artificial turf of claim 12, wherein the second yarns are more rigid than the first yarns.
 14. The artificial turf of claim 1, wherein the second yarns are made of a plurality of filiform formations arranged in tufts.
 15. The artificial turf of claim 1, wherein the first yarns have a first length, the second yarns have a second length at least equal to the first length, the first yarns extend to a first elevation from the upper surface, and the second yarns extend to a second elevation from the upper surface lower than the first elevation.
 16. The artificial turf of claim 1, wherein at least one of the first yarns, the second yarns and the third yarns is backstitched as tufts with the tufts having a tufting gauge between three sixteenth of an inch ( 3/16″) and three quarter of an inch (¾″).
 17. A method of manufacturing an artificial turf, comprising: stitching to a sheet member (1) first yarns having a first melting point, (2) second yarns distinct from the first yarns and having a second melting point, and (3) third yarns distinct from the first yarns and the second yarns and having a third melting point lower than the first melting point and the second melting point, wherein the first yarns, the second yarns and the third yarns extend upwardly from the sheet member; submitting the artificial turf to a heat treatment at a temperature equal to or above the third melting point but under the first melting point and the second melting point, whereby the third yarns at least partially fuses with at least one of the first yarns and the second yarns.
 18. The method of claim 17, further comprising maintaining the heat treatment between 2 seconds and 10 seconds.
 19. The method of claim 17, further comprising performing the heat treatment with a heat source of a temperature of between 125 and 225 degrees Celsius.
 20. The method of claim 17, wherein submitting the artificial turf to a heat treatment comprises having the yarns face a heat source. 